Which member in each pair has the greater dispersion forces? (b) CO 2 or CO, (c) SiH 4 or GeH 4 .

Hello everyone. Today. We are being asked to compare the inter molecular dispersion force of. We have two compounds here. And so the first thing we're gonna do is we want to go through our answer choices. So right off the bat we can see That answer. Choice A is the correct one. And in a minute we'll go through why each of the other ones aren't the same, Aren't the correct answers. So when evaluating these compounds, we have to look at the molecular weight first to determine what inter molecular force they may have. And since we only have carbon, hydrogen and bro means we know we can only stick with di pole dipole interactions. And so they both have the same weight. So both of these have a weight of 175 g per mole. They will have the same number of carbons, hydrogen and bromine atoms. When you have smaller molecular weight, you generally have weaker inter molecular forces. And since they're the same, we have to move on to our second factor. So we set our first factor as we look at the molecular weight for a second we look at branch versus linear. And we'd say that branched compounds will have higher boiling points due to having less surface area. And so since we'll say that branched will have less of a boiling point due to less surface area to cover. And so since the second compound here is branched, it has a weaker inter molecular force and therefore the linear chain which is the first compound will therefore have a stronger inter molecular dispersion force. I hope this helped, and until next time.

Ch.11 - Liquids and Intermolecular Forces

Brown - Chemistry: The Central Science 15th Edition

Brown15th EditionChemistry: The Central ScienceISBN: 9780137542970Not the one you use?Change textbook

All textbooks

Brown 15th Edition

Ch.11 - Liquids and Intermolecular Forces

Problem 23b,c

Chapter 11, Problem 23b,c

Which member in each pair has the greater dispersion forces? (b) CO₂ or CO, (c) SiH₄ or GeH₄.

Verified step by step guidance

Understand that dispersion forces, also known as London dispersion forces, are a type of van der Waals force that occur between all atoms and molecules due to the temporary fluctuations in electron density.

Recognize that the strength of dispersion forces generally increases with the size of the electron cloud, which is related to the molar mass and the number of electrons in the molecule.

Compare the molar masses of SiH4 and GeH4. Silicon (Si) has a lower atomic mass than Germanium (Ge), so SiH4 will have a lower molar mass than GeH4.

Consider the number of electrons in each molecule. GeH4 has more electrons than SiH4 because Germanium has more electrons than Silicon.

Conclude that GeH4, having a larger molar mass and more electrons, will have greater dispersion forces compared to SiH4.

Verified video answer for a similar problem:

This video solution was recommended by our tutors as helpful for the problem above.

Video duration:

Was this helpful?

Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Dispersion Forces

Dispersion forces, also known as London dispersion forces, are weak intermolecular forces arising from temporary fluctuations in electron density within molecules. These fluctuations create instantaneous dipoles that induce dipoles in neighboring molecules, leading to an attractive force. The strength of dispersion forces increases with the size and polarizability of the molecules involved.

Molecular Size and Polarizability

Polarizability refers to the ease with which the electron cloud of a molecule can be distorted by an external electric field or nearby charges. Larger molecules, like GeH4 compared to SiH4, generally have more electrons and a larger electron cloud, making them more polarizable. This increased polarizability results in stronger dispersion forces.

Comparative Analysis of Molecular Structures

When comparing molecular structures, it is essential to consider factors such as atomic size, molecular weight, and the number of electrons. In the case of SiH4 and GeH4, GeH4 has a larger atomic radius and more electrons due to the presence of germanium instead of silicon. This difference contributes to the greater dispersion forces in GeH4 compared to SiH4.